II Ok-NH-CO I where the two heterocycles art: joined at the 5-C through an ethylene chain. Derivatives of this type, with R= ethyl, propyl and benzyl, were prepared in 1911'by condensation of ethyl 1, 4-dialkylbutane-l, 1, 4, 4-tetracar-boxylate with urea. The substances are described as having no melting point up to 300, and no mention is made of their physiological properties. From the fact that no synthetic hypnotics are known with ...
